CN1115031C - Navigation assistance for call handling in mobile telephone systems - Google Patents

Abstract

In a mobile radio telephone system employing TDMA or CDMA, mobile units (5, 7) often must determine the timing and approximate power necessary for transmissions to a base station. Information broadcast by base stations allows the mobile station to approximate its distance from each base station (1) based on an average signal strength received and thereby determine the coarse sector location. Broadcast information may include the mean radial distribution of signal strength versus distance. From the broadcast information, the mobile station (5, 7) determines the propagation loss for a transmission to the base station and the appropriate power level and timing for transmissions. Accordingly, the mobile station (5, 7) transmits signals to the base station (1) at the determined signal timing and power level.

Description

Navigation aids for call handling in mobile telephony systems

field of invention

The present invention relates to the application of time-based multiple access methods, such as Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA) communication techniques in mobile cellular radiotelephone communication systems, and in particular to the control of such transmissions in a mobile station The scheme of transmitting power and timing of the way is controlled.

Background Art of the Invention

The cellular telephone industry has made remarkable strides in commercial activity in the United States and other parts of the world. The expansion of the central city area has far exceeded the expected rate and continues to exceed the capacity of the system. If this trend continues, the impact of this rapid growth will soon reach even the least developed regions. To meet the demand for increased capacity while maintaining a high quality of service and avoiding increased costs, improved technologies need to be provided.

Throughout the world, an important advance in cellular systems has been the change from analog to digital transmission. Equally important is the selection of an efficient digital transmission scheme for the implementation of the nascent cellular communication technology. In addition, it is generally believed that the original personal communication network (PCN), (using portable low-cost, small wireless phones, and can be used in homes, offices, streets and cars) can be completely replaced by a new digital cellular system structure and cellular carriers at cellular frequencies. A key requirement for these modern systems is the need for increased traffic capacity.

In mobile cellular radiotelephone systems using time-based multiple access methods such as TDMA or CDMA, mobile transmitters usually need to determine the appropriate transmit power according to the distance between them and the base station, and use the propagation delay between each and the base station related to accurate transmitter timing. Choosing the right transmitter power keeps all mobile transmitter signals received by the base station at roughly the same level, preventing excessive level differences that would cause interference from stronger signals.

In a TDMA system, the timing of a mobile transmitter's signal is controlled as a function of distance from the base station to ensure that the signal arrives at the base station in its exact assigned time slot and that there should be no overlap. Timing needs to be controlled in a CDMA system so that the width of the timing uncertainty region that a code-correlated receiver must search is reduced, especially when a mobile station first starts to transmit. In both systems, once the mobile station has achieved duplex communication with the base station, the information transmitted from the base station can continuously control the power and timing of the mobile station transmitter.

In the application of CDMA, the accuracy of power and timing is the most difficult to control. When signals overlap in time and frequency, it is of the utmost importance to maintain the correct power level. If there is no significant power level difference, the signals at the receiver may be separated due to the correlation between the received signal and the corresponding despreading code.

In conventional CDMA receivers, the suppression of unwanted signals in the correlation processing is limited by the so-called process gain. If the unwanted signal exceeds the wanted signal by more than the process gain, the wanted signal cannot be decoded.

In two US patents US5,151,919 and 5,218,619 entitled "CDMA Subtrative Demodulation" by the present inventor, such a system is proposed in which all signals are decoded at the base station in order from strongest to weakest signal. After decoding, and before demodulating the weaker signal, the stronger signal is subtracted from the composite signal. In this way, when the receiver distinguishes the order of the signals and their strengths, large level differences can be tolerated. However, even in this improved subtractive CDMA system, it is still difficult to deal with new signals with random signal levels, bursty and unpredictable.

The method of the present invention overcomes the problems in the prior art, and enables the base station to estimate the necessary power and/or timing advance, so as to transmit to the base station first.

Overview of the invention

The present invention proposes a method and apparatus whereby the information broadcast by the base stations in a multiple access, spread spectrum communication system enables the mobile station to adapt its distance to each base station according to the average received signal strength, and further enables the mobile station to estimate the necessary characteristics for transmission to the base station. In a basic embodiment, the broadcast information includes an average radius distribution of signal strength versus distance, independent of its direction of propagation. In another embodiment the difference in the radial distribution of signal strength in different directions is accounted for and additional information is broadcast by the base station for different sectors.

There are several ways to determine the approximate sector in which a mobile station is located. The mobile station can determine the surrounding base stations it can receive, or the base station can illuminate different approximate sectors with different frequencies, or a rotating signal strength map can be broadcast by the base station using a pair of phased antennas, the phase of the signal Associated with a flag in broadcast data to enable a mobile station to determine its bearing.

The mobile station receives the signal from the base station, measures the strength of each signal and takes the average value. After receiving the broadcast information from the base station, the mobile station determines the propagation loss for the transmission to the base station and uses the appropriate power in the opposite direction. In addition, the mobile station can use the radius transmission law to estimate the distance to the base station according to the sector it is in. Thus, the required timing advance can be estimated in order for the base station to receive the mobile station's transmission at the desired time.

Further, a mobile station can more accurately determine its sector and bearing by modulating the broadcast signal using a radionavigation modulation method that varies with the angle around the base station. For example, a base station broadcast signal can be transmitted from two separate antennas with continuously operating relative phase differences, resulting in a rotating signal strength map. The selected phase is related to a timing mark in the data modulation, thereby enabling the mobile station to determine its bearing relative to the base station. This radio navigation technology is known as the CONSOL system.

Base stations often use different powers to cover cells with different radii, and adopt different signal strength distributions in each cell. The broadcast information must therefore be adapted to each particular cell in order to enable mobile stations to determine its power and timing. Accordingly, another embodiment of the present invention does not have to employ expensive signal strength measurement operations when modifying broadcast information for each cell. Instead, during a conversation with the base station, the mobile station reports its received signal strength and the timing advance it employs. Therefore, the base station knows its own transmission ERP (effective transmission power) and the arrival time of the mobile station signal according to the reports from different mobile stations in a time period, so as to determine the distance of the mobile station and the relationship between the signal strength and the distance.

Another embodiment of the present invention is implemented when the base station performs CDMA transmission. By selecting the necessary parameters in the CDMA system, the surrounding base stations can reuse the same frequency. The advantage in terms of system capacity is that the number of simultaneous calls per square kilometer per megahertz of spectrum can be increased. In a CDMA system, a mobile station can simultaneously receive broadcast information from adjacent base stations as its currently assigned base station. When all base stations on the same frequency are making synchronous CDMA transmissions, the mobile station determines its position based on the relative timing of the three different receiving base stations. The broadcast information from the base station to the mobile station may include absolute base station coordinates for determining the absolute position of the mobile station or include the boundaries and orientation of the broadcasting base station relative to neighboring base stations. This enables the mobile station to determine its relative location.

Brief description of the drawings

The present invention is described in more detail below by way of example only and with reference to the accompanying drawings in the mode of the preferred embodiment of the present invention, wherein:

Figure 1 is a cellular coverage diagram for illustrating a cellular telephone system;

Fig. 2 is a block diagram of a base station of the present invention;

Figure 3 is a block diagram of a mobile station of the present invention.

Detailed description of the preferred embodiment

Although the following description is in the context of a cellular communication system involving a portable mobile radiotelephone and/or a personal communication network, those skilled in the art will appreciate that the present invention is also applicable to other communication modes. For example, the best implementation is described with respect to a CDMA system, however, in an FDMA or TDMA system, the invention can be used to avoid excessive signal level differences that would otherwise interfere with receiving The characteristic of machine selectivity deteriorates, or the timing for starting transmission is advanced in TDMA system.

Figure 1 is a simplified cellular coverage diagram in which cell _B0 covered by one base station is surrounded by adjacent cells _B1 to _B6 covered by respective base stations. For ease of illustration, assume that there is a mobile station located in cell _B0 . For simplicity, the cells are represented by circles of the same size, however, in practice, the area covered by different base station antennas may be a sector of a circle or an ellipse, or some variation of an irregular shape.

The base stations transmit CDMA signals on the same frequency, but each base station uses a different code. A mobile station receiver decodes the CDMA signal by associating a known sequence with the codes of the base station responsible for the mobile station and each neighboring base station, and listens to the broadcast channels of the neighboring base stations. Often a mobile station cannot pick up a base station's transmission. For example, a mobile station located at the adjacent edge of cells _B1 and _B0 may not receive a transmission from a base station in cell _B4 . However, the mobile station can know that a particular transmission cannot be received at its location and can therefore provide an indication that it is in one of six approximate sectors in cell _B0 .

The broadcast information from B ₀ preferably includes the signal strength distribution along the line B ₀ to B ₁ , and the signal strength distribution along the lines B ₀ -B ₂ , B ₀ -B ₃ and so on. The precise format of the signal strength distribution information is not important. For example, the signal strength distribution may be a table of signal strength expectations expressed in dBm at equally spaced distances from the cell center, or increments between sequential equally spaced rings, or a table of signal strengths at equally spaced distances, or is the coefficient of the power of the transmission distance used, for example, in a formula that uses signal strength as a function of distance or distance as a function of signal strength. Likewise, the same information is broadcast from other cells. Thus, if the mobile station can place itself in a sector across the line B ₀ -B ₁ by virtue of at least the information it can receive from B ₀ or B ₁ , it can pair distances along the line B ₀ -B ₁ Two alternate estimates are made, one starting at B ₀ and the other starting at B ₁ . Combine the two estimates. Get further estimates to reduce errors. If the mobile station can sometimes detect _B2 or _B6 , a further estimate of position can be made.

In the preferred embodiment, the base stations in cells B ₀ -B ₆ transmit synchronized CDMA codes, so that when a mobile station receives two base stations simultaneously or in close succession, the mobile station can be more precisely located at Correlated receivers on a certain hyperbola obtain timing differences. This hyperbolic navigation system allows the mobile station to be precisely located by receiving a third base station if necessary.

Further information required for the location of the mobile station is broadcast on each base station control channel, which includes the transmission range and bearing between each base station and its neighbors. Thus, B ₀ broadcasts the distances and bearings for lines B ₀ -B ₁ , B ₀ -B ₂ , B ₀ -B ₃ , etc., while B ₁ broadcasts the distances and bearings for lines B ₁ -B ₀ , B ₁ -B ₂ , B ₁ - B ₆ and so on for distances and angles. For ease of calculation by the mobile station, the distance is in units of the delay period of the CDMA slot chip (chip) cycle, not miles or kilometers.

The mobile station uses its estimated position and the base station's floating position to determine its distance from the base station in units of CDMA slot chip cycles. Then determine the appropriate time advance, and multiply the one-way propagation time by 2 relative to the timing reference obtained from the received base station signal, so that the return signal received by the base station is roughly consistent with the outgoing signal in time, and the time adjustment does not exceed A nominal difference, so that the mobile station transmits first to the base station.

For example, the broadcast information of the base station can be provided to each ring sector as shown in Table 1:

Table 1 If the mobile station receives this, then the signal strength of the distance at which the mobile station is located may be

-40dBm 300 meters

-50dBm 800 meters

-60dBm 2315 meters

-70dBm 5240 meters

-80dBm 8771 meters

-90dBm 14308 meters

-100dBm 23580 to

-110dBm 40980 meters

-120dBm 65000 meters

The mobile station can then use the measured signal strength values to interpolate between table entries to obtain an estimate of the distance. In this way, the mobile station can know the round-trip propagation delay, which is equivalent to the time to travel twice the distance at the speed of light. In this way, the mobile station can calculate how much the timing of its transmitted signal should be advanced relative to the reception of the signal by the base station, so that the return signal can reach the base station according to the expected timing relationship. In practice, if the time is converted in advance by a certain unit, for example, the distance information is broadcast in units of 1/4 time slot, the calculation of the mobile station can be greatly saved.

This is the crudest example of a position determination system, and the actual signal strength versus distance curve appears non-monotonic due to ground irregularities or shadows. To reduce outliers and improve performance, a way to estimate distance from several receivable base stations can be used. If no neighboring base stations are received, the mobile station is likely to be in the approximate center of a cell from which a transmission can be received. Another known method of improving the accuracy of primitive navigation systems is to employ Kalman filtering. These approaches make the estimated position relatively flat, thereby limiting the ability of the mobile station to make instantaneous changes in position or velocity, preventing instantaneous position or velocity changes, and allowing only modest accelerations, eg, less than 0.2g.

Further measures may include synchronizing the CDMA transmissions from the base stations so that the mobile station can determine the relative arrival times of the signals, and consequently the incremental distances. This constitutes an elliptical navigation system, since the trajectory of possible mobile station positions at a given incremental distance from two base stations is an ellipse. A CONSOL position determination system can also be used here, in which the base station uses a phased array antenna to transmit signals, so that the signal received by the mobile station has a change feature in the 360-degree azimuth away from the base station. A mobile station determines its position by measuring this characteristic. By determining the bearings from the two base stations, the mobile station can be located. The base station broadcast information should include the base station coordinates used in such calculations.

In TDMA systems, for example, different mobile stations are allocated different time slots in the uplink and downlink directions. A first mobile station's signal may be placed in a first time slot for downlink transmission, a second mobile station's signal may be placed in a second time slot immediately following the first time slot, and so on. Conversely, in the uplink, a first mobile station transmits in the second time slot, a second mobile station transmits in the third time slot, and so on. The first mobile station receives the first time slot and transmits during the second time slot, therefore, the mobile station does not necessarily have to transmit and receive at the same time.

Since the distance between the mobile station and the base station varies, the signals transmitted by the base station are received with different time delays. Thus, if the mobile station turns around and transmits after receiving, the base station receives the transmitted signal with an offset of one slot plus the round-trip delay. This makes it possible for the signal received by the remote mobile station to be delayed or even to overlap and interfere with a signal from a nearby mobile station in the next time slot. Therefore, a TDMA mobile station can advance its transmit timing by twice the cyclic propagation delay so that its transmitted signal arrives in the correct time slot. In order to ensure that the transmit timing does not intrude on the receive timing, the overall uplink slot format is offset from the downlink slot format by an amount slightly greater than one slot, that is, the offset corresponds to the maximum range of the mobile station. The maximum timing advance that must be provided at

In a CDMA system, it is not necessary to divide the transmission format into time slots. Allowed overlap is usually already taken into account for mobile stations. However, avoiding excessive relative delays between different mobile stations is still an important issue for several reasons. First, it may be necessary to use orthogonal spreading codes for different mobile stations. Orthogonal spreading codes have zero correlation with each other. Therefore, mobile stations using these codes will not interfere with each other even if they overlap in time and frequency. However, orthogonality can only be maintained if the codewords are positioned exactly on top of each other. Orthogonality may be lost if the codes have a relative offset of one slot slice or more. It is therefore desirable for mobile stations to advance their transmission times according to their distance from the base station so that they receive their orthogonal CDMA codes exactly on top of each other to within a fraction of a slot chip accuracy. This can be achieved by a feedback loop, including a bit in the base station's downlink transmission that periodically indicates an appropriate small amount of lead or lag when double talk has started. It is an object of the present invention to obtain the proper timing as accurately as possible before the call is set up and double talk is effected. This is required because it is equally difficult for a base station to detect a call from a CDMA mobile station without knowing which code location to use to despread the CDMA signal. The base station searches for the mobile station's call at intervals of one slot slice using the correlation code at various offsets. However, if the slot slice is only 0.8 microseconds long, and since the delay from 0 to 30 km distance is only 0-200 microseconds, the delay is also non-deterministic, so it is difficult to complete with 250 relative code offsets search. It is therefore desirable to pre-adjust the transmission timing of the mobile station prior to call setup in order to reduce timing inaccuracies faced by the base station.

The preferred embodiment of the invention is described below with the aid of Figures 2 and 3, which respectively show block diagrams of a suitable base station and a mobile station. In Fig. 2 a base station CDMA transmitter 1 is shown which transmits a plurality of superimposed signals on the same frequency using different codes. Some of the signals are traffic carrier channels used to carry coded speech signals of different mobile stations. At least one overlapping signal is the broadcast and call channel, which is used to broadcast some information to all mobile stations, and also includes a mobile station ID code or telephone number in the message to relay a certain call to a specific mobile station, the control computer 3. Provide broadcast information to the CDMA transmitter 1, which broadcast information is related to the position estimation function of the mobile station. The following information is included on the broadcast channel: (i) the distance to each adjacent base station in the unit of CDMA slot cycle; (ii) the orientation with each adjacent base station, in units of π/128; (iii) the CDMA code used by each adjacent base station; (vi) the base station transmitter power in dBW; and (v) at each point along the line leading to each adjacent base station, at 0 dB antenna gain, The expected average signal strength received by the mobile station receiver at intervals delayed by one CDMA slot chip period, encoded in dB increments between sequential points, where the first value is Absolute value in dBm.

The base station control computer 3 collects information from mobile stations through the CDMA receiver 2, so that the control computer 3 can acquire and continuously update broadcast information. The broadcast information is transmitted from the mobile station to the base station by using the auxiliary control channel (ACCH) during the service call using the called channel, and the broadcast information and service information are multiplexed. The information transmitted by the mobile station includes: (i) the transmitter power level used by the mobile station; (ii) the currently used mobile station timing advance in units of slot slice cycles; (iii) the time slot used to maintain the current call , the current signal strength received from the base station, the unit is dBm; (iv) the average signal strength of the same frequency received from all surrounding base stations (for example, within the last 2 seconds), and the calling channel of this frequency has just (that is, in within the previous 2 seconds) was successfully demodulated; and (v) the relative delay between signals received from other base stations and signals received from the currently assigned base station, in units of CDMA slot slice cycles.

The control computer 3 processes all the above information with an approximate position determination program to determine the position of the mobile station. A signal strength map is constructed in a cell by averaging the signal strength reported by a mobile station at a determined location and previous reports from other mobile stations indicating approximately the same location. Use the average signal strength graph to provide the base station with the information it needs to broadcast.

The block diagram of the mobile station in this embodiment is shown in FIG. 3 . The mobile station CDMA transmitter 5 and the mobile station CDMA receiver 6 have a fixed frequency offset in operation, so a duplexer 4 can be used to connect them to the same mobile antenna. The CDMA transmitter 5 in the mobile station only transmits a CDMA coded signal. In contrast, the base station CDMA transmitter 1 transmits using many different codes. The code used by the mobile station transmitter 5 is instructed by the mobile station control processor 7 . However, the mobile station CDMA receiver 6 is able to associate many different codes provided by the control processor 7, and thereby simultaneously demodulate many overlapping CDMA signals. The demodulation technique adopted is preferably a combination of Walsh-Hadamard orthogonal coding of subtractive CDMA demodulation and scrambling, as described in the above-mentioned U.S. Patents 5,151,919 and 5,218,619. The signal is demodulated by the CDMA receiver.

Additionally, a technique known as RAKE reception, such as that described in pending patent application No. 857,433 entitled "Diversity RAKE Receiver," may be used. The RAKE receiver is used to perform correlated reception on input signal samples with different time offsets, thereby solving the timing inaccuracy and echo problems, and combining the results of correlated reception with correlated weighting or non-correlation weighting. The results of the correlated reception performed with different time offsets are also transmitted to the control processor 7 in order to determine the time difference of arrival between the different signals.

The signal demodulated by the mobile station includes the broadcast channel of the cell in which the mobile station is located and the broadcast channels of any adjacent cells whose received signal strength exceeds a certain threshold. When talking to the base station, the mobile station receiver 6 also demodulates a service-oriented CDMA signal transmitted by the base station and modulates the mobile station transmitter with the service signal, such as digitally encoded speech.

The mobile station receiver receives various data on the broadcast channel of its designated base station. In this way, the mobile station can estimate the distance between it and the base station according to the average received signal strength, and this distance is represented by the time delay with the CDMA time slot cycle as the unit. CDMA receiver 2 provides control computer 3 with an indication of instantaneous signal strength in the form of correlation measurements of received signals at different time offsets. The control computer combines the energies from the related measurements to calculate a running average of the total energy.

The broadcast channel of the base station is preferably programmed in a time-multiplexed format of 16 message slots each occupying an interval of 20 ms, with a repeated cycle every 320 ms. When the network calls a mobile station, the call is transmitted in a time slot according to the last digit or mobile station telephone number or ID code. During the remaining time slots, the mobile station can "sleep" and save battery power for 15/16 of the time, and only capture data during the designated time slots. The mobile stations that can be called in a particular time slot are collectively referred to as a "sleep mode group". Usually, the mobile stations in the dormant mode group need not be associated with a telephone number, but are each associated with an independent internal program code.

According to the broadcast channel format, the mobile station may wake up in another time slot during which information related to the position estimate is broadcast. In the preferred embodiment, this information is broadcast during the idle time between calls made by the network to the mobile station. All base stations are preferably synchronized to broadcast this information at the same time. This prevents the mobile station from waking up in other time slots when receiving neighboring base stations.

The mobile station control processor 7 receives signal strength and relative time measurements from all neighboring base stations that can be detected from the CDMA receiver 6, and provides broadcast information on the relative distance and bearing between the neighboring base stations and along the direction to the neighboring base stations. The expected signal strength distribution in the radial direction of the base station.

The mobile station control processor 7 processes all of the above information in the location finding or navigation procedure. The program includes different modes that work depending on whether or not neighboring base stations can be heard. In one mode, neighboring base stations cannot be heard, so the navigation program must rely solely on received signal strength to estimate its distance from a given base station. The sector in which the mobile station is located may be determined from past records. For example, _a mobile station is considered to be in a sector spanning the line _B0 - _B1 if it was locked in _B1 before moving into the current cell B0. If a neighboring base station cannot be heard, the navigation program assumes the mobile is within 70% of the cell's maximum radius and begins to use broadcast signal strength versus distance information to further estimate the mobile's position.

In another mode, at least one neighboring base station can be heard. The distance to two base stations can be estimated according to the signal strength, and the distance difference between the base stations can be estimated according to the timing difference between received signals. This provides a more accurate estimate of the mobile's distance from its own cell center. If three or more base stations can be heard, the mobile station is located by elliptical navigation calculations.

The accuracy of the position estimation procedure can be improved by taking into account the finite velocity of the mobile station. Take for example the known Kalman filtering technique, which can be used to ensure the estimation of the position and velocity of the mobile station.

The Kalman technique works as follows; (1) using past position and velocity estimates at the deduced mobile station position to obtain a new estimate; (2) using broadcast information from base stations corresponding to the (3) Compare the actual signal strength and timing difference measurements with the estimates, and update the position and velocity estimates accordingly.

Once an estimate of the distance to the base station is obtained, the mobile station transmits to the base station for the first time with an appropriate timing advance equal to twice the propagation delay over that distance. Control processor 7 provides timing advance to CDMA transmitter 5 .

The mobile station can also use the power level of the first contact in terms of the average received signal strength. The potential cost is the average propagation loss from the mobile station transmitter to the base station receiver, which is the same as the average propagation loss in other directions. Thus, if the base station transmitter power and received signal strength are known, the mobile station transmitter power can be calculated at the base station to obtain the desired received signal strength.

When necessary, the base station broadcast information includes information on the ERP of the broadcast signal. The mobile station correlates the received signal strength with the ERP to determine the propagation loss in the downlink direction. Unless the broadcast information of the base station has indicated that the gain of its receiving antenna is different from that of its transmitting antenna, the mobile station will consider the downlink propagation loss to be the same as the loss in the uplink direction, and the difference in antenna gain is called outgoing/incoming ( talk-out/talk-in) is poor. In this case, the mobile station uses this coefficient to convert the downlink propagation loss to an estimate of the uplink propagation loss.

Random access messages are transmitted from the mobile station to the base station at the calculated power level and timing. The main information in the random message is the identification number of the mobile station. The random access procedure is substantially complete when the base station replies with a message to the same mobile station identification number. A message from the base station may instruct the mobile station to switch to a different radio frequency and code in order to maintain the current call. Once duplex communication is achieved, the mobile station reports received signal strength and timing to the base station in the manner described above. The base station control processor 3 processes this information in order to update the signal strength map within the cell.

Although the present invention has been shown and described in terms of particular embodiments, it should be understood that the invention is not limited thereto since modifications may be made by persons skilled in the art. This application includes any modifications that fall within the scope and spirit of the description and claims of the invention.

Claims (25)

1. A method for realizing communication between a mobile station and a base station in a multiple access spread spectrum communication system, comprising the following steps: broadcasting a signal from at least one base station to said mobile station, wherein the broadcast signal from said at least one base station includes data; receiving broadcast signals of said at least one base station at said mobile station; determining an average signal strength for said received broadcast signal; and The distance between the mobile station and the at least one base station is estimated based on the data in the received broadcast signal and the average signal strength. 2. according to the method for claim 1, also comprise the following steps: determining a signal transmission timing based on data in the broadcast signal and the estimated distance; and Signals are transmitted from the mobile station to the at least one base station according to the determined signal transmission timing. 3. The method of claim 1, wherein said data in said broadcast signal includes signal strength as a function of distance from said at least one base station. 4. The method of claim 3, wherein said data in said broadcast signal further includes at least one of distance and propagation time delays from said at least one base station to neighboring base stations. 5. The method of claim 4, wherein said data in said broadcast signal further includes a bearing from said at least one base station to said adjacent base station. 6. The method of claim 5, wherein said data in said broadcast signal further includes an absolute location of said at least one base station, and an identification code for uniquely identifying said at least one base station. 7. The method according to claim 1, further comprising reporting from said mobile station to said at least one base station an estimate of the distance between said at least one base station and said mobile station and the average signal strength received by said mobile station step. 8. according to the method for claim 7, also comprise the following steps: determining signal transmission timing based on the timing reference in the broadcast signal data and the estimated distance; and The determined transmission timing is reported from the mobile station to the at least one base station. 9. The method according to claim 8, further comprising the step of averaging previously reported signal strengths of other mobile stations at similar distances from said at least one base station, thereby determining said at least one base station at said at least one base station Signal strength at different distances. 10. The method according to claim 9, further comprising: reporting from other mobile stations estimated distances between said other mobile stations and said at least one base station; Each other mobile station is identified at an approximate distance from the at least one base station according to the reported estimated distance. 11. The method according to claim 10, wherein the other base stations share a common timing reference with said at least one base station. 12. The method according to claim 11, further comprising the steps of: reporting from said other base station to said at least one base station the time of arrival of a mobile station signal over a radio link or landline network relative to a timing reference of said at least one base station; and The distance of said other mobile station to said at least one base station is identified using the time-of-arrival report and the reported estimated distance. 13. A method for implementing communication between a mobile station and a base station in a multiple access, spread spectrum communication system, comprising the steps of: broadcasting a signal from a first base station to said mobile station, wherein said first base station broadcast signal includes first information including signal strengths at different distances in a general direction from said first base station towards a second base station distributed; broadcasting a signal from said second base station to said mobile station, wherein said second base station broadcast signal includes second information comprising signals at different distances in a general direction from said second base station toward the first base station intensity distribution; measuring the average signal strength of the first base station broadcast signal and the second base station broadcast signal; determining whether the orientation of the mobile station to the first base station is in the general direction of the second base station based on the first information, the second information, and the measured average signal strength; and If the bearing is in the general direction of the second base station, the distance from the mobile station to the first base station is estimated using the first base station signal strength distribution. 14. The method according to claim 13, wherein said first information includes a unique identification code for identifying said second base station. 15. A method for effectuating communication between a mobile station and a base station assigned to said mobile station in a multiple access, spread spectrum communication system, comprising the steps of: receiving broadcast signals from designated base stations at the mobile station; Measuring the received signal strength of broadcast signals; estimating the location of the mobile station based on received signal strength; and Based on the estimated position, an appropriate timing advance is determined for transmitting signals from the mobile station to the designated base station. 16. The method according to claim 15, further comprising the steps of: receiving broadcast signals from at least one neighboring base station; and The timing difference between broadcast signals received from the at least one neighboring base station is measured, and the step of estimating the position of the mobile station is further performed according to the measured timing difference. 17. The method of claim 16, wherein said broadcast signal from said at least one neighboring base station includes a signal strength distribution along a line connecting a given base station and said at least one neighboring base station. 18. The method according to claim 17, further comprising the step of: receiving a broadcast signal from a first neighboring base station and a second neighboring base station, the broadcast signal comprising a signal between said first neighboring base station and said second neighboring base station The transmission distance and azimuth between them, the first adjacent base station and the second adjacent base station are adjacent to each other. 19. The method according to claim 17, wherein said broadcast signal received by a mobile station is transmitted synchronously from said designated base station and said at least one neighboring base station. 20. The method of claim 15, wherein said position estimating step further comprises the step of estimating the velocity of the mobile station. 21. A method according to claim 20, wherein the estimated velocity is determined using a Kalman filtering technique. 22. The method of claim 15, wherein said timing advance corresponds to twice the propagation delay over the distance from the mobile station to the designated base station. 23. A method for effectuating communication between a mobile station and a base station assigned to said mobile station in a multiple access, spread spectrum communication system comprising the steps of; broadcasting signals from adjacent base stations and designated base stations, the broadcast signals including position information; receiving broadcast signals at said mobile station; calculating the position of the designated base station and the neighboring base station relative to the mobile station based on the broadcast signal; estimating a distance from the mobile station to a designated base station and a signal timing for transmitting a signal from the mobile station to the designated base station according to the calculated bearing; and The signal is transmitted from the mobile station to the designated base station in accordance with the estimated signal timing. 24. The method of claim 23, wherein said estimating step further comprises determining a propagation delay from said mobile station to said designated base station, wherein said signal timing is approximately twice said propagation delay. 25. The method of claim 24, wherein said broadcast signal is broadcast using a phased antenna.

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